Lemneolemnanes A–D, Four Uncommon Sesquiterpenoids from the Soft Coral <i>Lemnalia</i> sp.

Abstract

Four undescribed sesquiterpenoids, lemneolemnanes A–D (1–4), have been isolated from the marine soft coral Lemnalia sp. The absolute configurations of the stereogenic carbons of 1–4 were determined by single-crystal X-ray crystallographic analysis. Compounds 1 and 2 are epimers at C-3 and have an unusual skeleton with a formyl group on C-6. Compound 3 possesses an uncommonly rearranged carbon skeleton, while 4 has a 6/5/5 tricyclic system. Compound 1 showed significant anti-Alzheimer’s disease (AD) activity in a humanized Caenorhabditis elegans AD pathological model.

Keywords

• soft coral
• <i>Lemnalia</i> sp.
• sesquiterpenoids
• anti-Alzheimer’s disease activity